Existing methods for assessing disease status and responsiveness to treatment in Fibromyalgia (FM) have been criticized on the grounds that (a) existing patient reported outcomes measures (PROs) fail to adequately assess the domains of relevance to patients with FM, (b) most existing instruments have been borrowed from other diseases and thus disease-specific PROs are largely undeveloped for FM, and (c) many of the existing measures have unfavorable psychometric properties and/or lack sufficient sensitivity to change. Thus, there is need for new methodologically sound PROs for FM that can be delivered in a traditional manner in the short term and via the more sensitive and efficient methodology associated with computer adaptive testing (CAT) in the longer term. Lack of consensus regarding the relevant assessment domains for FM has prevented the development of meaningful multi-dimensional instruments for FM;but recent agreement between projects within the WHO ICF initiatives and within OMERACT suggests that the time is right to initiate this type of instrument development. To this end, this proposal contains four aims: In the first, focus groups of FM patients will be conducted by the National Fibromyalgia Association (NFA) so as to generate disease-specific items that can supplement the more generic chronic illness item banks being developed by the NIH roadmap initiative PROMIS. Aim two will field test the disease-specific items along with the PROMIS item banks in a large representative sample of FM patients recruited through the NFA. A series of validation studies will be conducted under Aim three so as to support the use of the new disease- specific scales for administration in clinical trials in a traditional manner. Finally, under aim four, a CAT algorithm utilizing the combined PROMIS and FM disease-specific items will be developed and field tested. The final goal of this project will be the integration of the new FM-CAT module into the PROMIS network. The investigators of this proposal are already actively collaborating with ICF, OMERACT, and PROMIS, have track records in successful outcomes measurement development and advanced quantitative methods and possess clinical expertise in FM. The products resulting from this project will have direct applicability and utility in clinical trials involving FM and represent the next critical steps in refining the ability to identify useful and meaningful treatments for this refractory condition. This project is relevant to public health as it will provide a disease-specific measurement instrument to use in clinical trials thus leading to more effective methods for assessment and treatment of Fibromyalgia.